Warm the sausages in hot water. Cut open the buns. Cut the gherkins into slices. Wash the lettuce leaf, dab dry and cut in half. Put 1/2 lettuce leaf in each roll.
Take the sausages out of the water and put 3 in each roll. Halve the onion slice. Put mustard and ketchup in a piping bag and spray on the sausages. Cover with cucumber slices and onion